Electronic article surveillance (EAS) includes the tracking and/or detecting the presence or removal of items from warehousing, inventory, or a retail establishment. EAS is achieved by applying an EAS element as part of a security tag to the item or its packaging and when the security tags are exposed to a predetermined electromagnetic field (e.g. pedestals located at a retail establishment exit), they activate to provide some type of alert and/or supply data to a receiver or other detector. In the electronic article surveillance (EAS) industry, a “hard tag” refers to either a re-usable or disposable tag which is intended to be removed from an article, e.g., merchandise at the point of sale to be re-used on other merchandise or thrown away. Hard tags typically are constructed to contain an EAS element, which may be for example an acousto-magnetic element (AM), a radio frequency element (RF), or electro-magnetic element (EM). Tags may also be constructed to contain a radio frequency identification (RFID) element, which may respond at low, high, or ultra-high frequencies.
An EAS element may include a resonant circuit with a coil coupled to a capacitor. The EAS security element is tuned to a predetermined frequency and if one attempts to remove the hard tag with the security element from a store, an alarm triggers as the tag passes through a surveillance field created by a transmitter and receiver located between pedestals at the store exit, tuned to the same frequency. The alarm goes off as the EAS element resonates, providing an output signal detected by a receiver, also located in the pedestals.
An RFID element typically includes an integrated circuit (IC) and an RF LC circuit (resonant circuit) or antenna (e.g. a dipole antenna), tuned to a predetermined RF frequency. Often, the integrated circuit (IC) comprises memory that has been programmed with information associated with the article (e.g., product ID information such as a serial number, unique identification number, price, etc.). When a transmitter emits a signal at the predetermined RF frequency and threshold value which is received by the tuned antenna, the RFID element emits a signal containing the stored information which is then received by a receiver and the information demodulated from the element-emitted signal. This information can then be used for, among other things, determining whether to set off an alarm or not. The RFID tag may also be used for merchandise visibility and inventory control, to identify where a tag and associated product are located or where they have moved to or from within the store.
As an alternative to an EAS element embedded in a hard tag, the hard tag may be equipped with a benefit denial device. A benefit denial tag typically includes ink releasing elements, such that when an attempt to break the tag from a product is performed, glass vials of ink shatter within the tag, ultimately leaking about the product which devalues the product and likewise to provide notification to the retailer that that particular merchandise was tampered with.